The present invention is directed to ink compositions and, more specifically, the present invention relates to semi-solid hot melt inks with for example, a melting point of from between about 25.degree. C. and about, 50, preferably to about 40.degree. C., especially useful for acoustic ink printing, processes and apparatuses, reference, for example, U.S. Pat. No. 5,121,141, U.S. Pat. No. 5,111,220, U.S. Pat. No. 5,128,726, U.S. Pat. No. 5,371,531, the disclosures of which are totally incorporated herein by reference, including especially acoustic ink processes as illustrated in a number of the aforementioned copending applications and patents, such as an acoustic ink printer for printing images on a record medium.
The inks of the present invention in embodiments thereof are comprised of (1) a liquid non-aqueous vehicle with a boiling point of higher than about, or about equal to 150.degree. C. and lower than about, or about equal to 350.degree. C., and more specifically from about 175 to about 325 degrees Centigrade, and yet more specifically from about 225 to about 300 degrees Centigrade, and with a low acoustic loss to for example, reduce, or minimize energy consumption, and which acoustic loss is below, or about equal to 60 dB/mm, (2) a solid additive that can be contained in the ink, or a substrate, such as paper pores and with a melting point of lower than about, or equal to about 75.degree. C. and preferably between about 35 to about 74.degree. C. and with a low acoustic loss to reduce, or minimize energy consumption, and which acoustic loss is for example, below about, or equal to about 100 dB/mm, (3) a light fastness UV absorber, (4) a light fastness antioxidant, (5) and a colorant such as a dye, a pigment or mixtures thereof. More specifically, the present invention is directed to semi-solid hot melt acoustic ink compositions comprised of (1) nonaqueous liquid vehicles having a boiling point higher than about 150.degree. C. and lower than about 350.degree. C., preferably between about 170 to about 300.degree. C., and with low an acoustic loss below about 60 dB/mm, and preferably in the range of from about 5 to about 40 dB/mm, (2) a nonaqueous solid additive with a melting point of lower than about 75.degree. C. and preferably between about 35 and 74.degree. C., with a low acoustic loss below about (throughout below, and higher include about equal to also) 100 dB/mm, and preferably in the range of from about 25 to about 80 dB/mm, (3) a UV absorber, (4) an antioxidant, (5) a colorant, and wherein there can be generated with such inks excellent developed images on plain and coated papers with acceptable image permanence, excellent projection efficiency on transparencies without a post fusing step, and excellent crease resistance, and wherein the inks possess acceptable, and in embodiments superior lightfastness, and superior waterfastness. Moreover, in embodiments of the present invention there is enabled the elimination, or minimization of undesirable paper curl since water need not be present in the invention inks, and it is preferred that there be an absence of water, and since water is not present in the inks a dryer can be avoided thereby minimizing the cost of the acoustic ink jet apparatus and process.